Computer Science – Sound
Scientific paper
Dec 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007agufmsa31a..07t&link_type=abstract
American Geophysical Union, Fall Meeting 2007, abstract #SA31A-07
Computer Science
Sound
2437 Ionospheric Dynamics, 3332 Mesospheric Dynamics, 3369 Thermospheric Dynamics (0358), 3389 Tides And Planetary Waves
Scientific paper
The Ionosphere-Thermosphere-Mesosphere (ITM) region is highly variable and has a complex system of drivers including variable solar radiation, geomagnetic activity, and forcing from the lower atmosphere. Waves that originate in the troposphere grow in amplitude as they travel upwards into decreasing density at higher altitudes where they become the most prominent dynamical features of the ITM. Planetary and gravity waves modify the zonal mean temperature and winds through dissipation and momentum deposition. The effects of these waves on the ITM are expected to depend on the level of solar activity. For all types of waves, how high they penetrate into the thermosphere depends on the temperature, wind, and viscosity profiles. Current observations have shown signatures of both gravity waves and planetary waves in upper atmospheric measurements of winds, temperature, and ion density. The momentum deposition from upward propagating waves is thought to generate the quasi-biennial oscillation (QBO) and semiannual oscillation (SAO) in the zonal circulation of the stratosphere and mesosphere. These zonal wind oscillations, in turn, modulate the waves as they propagate upwards, including the migrating and nonmigrating tides. Understanding the behavior of the tides is not only crucial to characterizing mesopause variability but also transport in the region. Momentum deposition by the diurnal tide at low latitudes in the lower thermosphere produces indirect circulations that will transport neutral and ionized constituents both vertically and horizontally to higher latitudes. Six years of measurements by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite and longer time series from the Super Dual Auroral Radar Network (SuperDARN) HF radars are analyzed to examine the seasonal and inter-annual variations of the diurnal, semidiurnal and terdiurnal tides in the mesosphere and lower thermosphere. We present estimates of both the migrating and nonmigrating of these tides from the lower stratosphere to the lower thermosphere and discuss evidence of nonlinear interaction between the tides and other wave modes. We also examine the inter-relationship the tides may have with lower and middle atmosphere variability (e.g., QBO, SAO, and stratospheric warmings) and tidal impacts on the zonal mean structure of the upper atmosphere and ionosphere using additional data from TIMED/GUVI and TOPEX/Jason data.
Christensen A.
DeMajistre Robert
Mlynczak M. M.
Paxton Larry
Ruohoniemi Michael J.
No associations
LandOfFree
Inter-annual and long-term variations observed in the ITM system does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Inter-annual and long-term variations observed in the ITM system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inter-annual and long-term variations observed in the ITM system will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1412480